Supermarkets today typically use three single stage compressors in parallel which turn on and off on suction pressure. Such systems typically have no economizer and thus the efficiency is low because the compression ratios are high and there is much cycling of the compressors and the suction pressure control band is still quite wide. These factors contribute to inefficiency and lack of reliability.
It is, therefore, a primary object of the present invention to provide an improved multi-compressor refrigeration system in which the basic system still employs only three compressors, one booster and two high stage compressors, wherein the system employs an economizer which is constantly active within the system and which requires only two basic transducers for total system control.